Personally, I like the C++ language. Here are some free tutorials on C++ :
http://www.cprogramming.com/tutorial.htmlhttp://www.cplusplus.com/doc/tutorial/These two tutorials rock. They are really really good.
Once you've mastered "ANSI" C++ , then you can learn how to do Amiga specific stuff by getting the Rom Kernal Manuals from somewhere. They are included on the Amiga Developer CD, which should be available from Haage&Partner or any other good Amiga dealer. I got mine from Anything Amiga in Australia for about $45 Australian dollars (cant remember exactly.)
The Amiga Developer CD also has a free C/C++ compiler called StormC 3.0. It's very easy to use.
To anyone who wants to get into coding.. if you really want to program, follow my advice! Good luck! And if you get stuck with something, ask for help on this forum!!